Phosphate incorporation into the total protein fraction, calcium uptake and cyclic nucleotide levels of smooth muscle cells derived from normotensive WKY or SHR-SP and SHR-SR have been studied under basal and stimulated conditions. Cell stimulation was induced by high potassium, phenylephrine and isoproterenol. No differences in phosphate incorporation or calcium uptake were observed, when WKY were compared to SHR under any conditions. In all cell types, potassium enhanced calcium uptake; this effect was abolished by isoproterenol. Cyclic AMP levels were increased in all cell types following isoproterenol treatment. This increase was most profound in SHR-SR and SHR-SP. The effects of isoproterenol on calcium uptake and cyclic AMP accumulation are probably unrelated as the extent of cAMP accumulation does not correlate with the attenuation of calcium uptake after high potassium exposure. The potential relationship of cAMP accumulation to hypertension is discussed.